People who have ever tried to use standard hook_form_alter() tricks with CCK fields are easily recognizable: there are huge bald spots where large chunks of their hair used to be, and dark strings of swear words often erupt from the corners where they're working.
The basic reason for this is that CCK fields are "special," since they essentially set up templates for building form fields. Very meta. If you look at a CCK field in hook_form_alter() you'll see a structure kind of like...




